1. Field of the Invention
The present invention relates to a coordinate input apparatus. More particularly, the present invention relates to a coordinate input apparatus provided with means for determining whether, when a stick-type operation section provided in a keyboard device or the like is operated, the operation is a normal stick operation or a switching operation.
2. Description of the Related Art
Hitherto, as keyboard devices, there are known a type having only various operation keys arranged in a predetermined sequence in the operation section and a type (hereinafter, this type will be referred to as a "keyboard device with a stick-type operation section") having such operation keys and one stick-type operation section (stick pointer) at a predetermined position among the operation keys.
Meanwhile, in a known keyboard device with a stick-type operation section, a distortion gauge (a total of four distortion gauges) is bonded onto each side of the base portion of the stick-type operation section along two directions, i.e., along the X direction and the Y direction, intersecting at right angles to each other. These distortion gauges are structured in such a way that two distortion gauges are connected in series between a DC power supply and a ground in each of the X and Y directions, and outputs corresponding to operational pressures (load forces) in each of the X and Y directions are guided out from the connection points of the two distortion gauges which are connected in series. When the tip of the stick-type operation section is pressed in a desired direction by the fingertip of the key operator, the load force applied to the stick-type operation section is applied to the respective distortion gauges in each of the X and Y directions, causing each of the values of these distortion gauges to vary. At this time, changes in these resistance values are detected as voltage changes in each of the X and Y directions, and thus by reading the detection output, load data indicating the load force at the tip of the stick-type operation section is obtained. Then, the obtained load data is subjected to digital conversion and other data processing and is converted into coordinate data within the keyboard device with a stick-type operation section. Next, the coordinate data is transmitted from a communication control section within the keyboard device with a stick-type operation section to a main unit, such as a personal computer, through a cable.
On the main unit side, the coordinate data supplied from the keyboard device with a stick-type operation section is appropriately processed, after which the data is supplied to a display section, causing a cursor displayed on the display section to move. In this case, the movement direction of the cursor is determined in response to the direction of the pressing operation applied to the stick-type operation section, and the movement speed of the cursor is determined in response to the magnitude of a load force during a pressing operation applied to the stick-type operation section.
In the keyboard device with a stick-type operation section, when the key operator presses the tip of the stick-type operation section in a desired direction, a load force due to the pressing operation is applied to the respective distortion gauges in each of the X and Y directions, causing each of the resistance value of these distortion gauges to vary. Changes in these resistance values are detected as voltage changes in each of the X and Y directions and are formed into load data along the X and Y directions.
Some keyboard devices with a stick-type operation section have, as an operation function in the stick-type operation section, an operation function which assumes an impact load force obtained when the tip of the stick-type operation section is struck as a switching operation, in addition to the operation function for pressing the tip of the stick-type operation section in a desired direction. In such a case, in the keyboard device with a stick-type operation section having the switching operation function, a pressure sensor, for example, an auxiliary distortion gauge, for detecting an impact load force along the length direction (Z direction) is disposed additionally in the base portion of the stick-type operation section. In this auxiliary distortion gauge, load data along the Z direction indicating the impact load force of the stick-type operation section is detected, and the detected Z-direction load data is processed together with the X-direction and Y-direction load data. Then, the processed load data along the X and Y directions are transmitted as coordinate data, and the processed load data along the Z direction is transmitted as switch data from the communication control section to the main unit, and the cursor position corresponding to the coordinate data and the switch data supplied to the display section of the main unit is displayed.
The known keyboard device with a stick-type operation section having a switching operation function is capable of detecting a pressing operation of the stick-type operation section and a switching operation of the stick-type operation section. However, when a switching operation is detected, and when the detection output is to be converted into switch data, it is necessary to additionally dispose an auxiliary distortion gauge (pressure sensor) and a specific circuit element for performing the conversion process. Therefore, there arises problems in that the construction of the keyboard device becomes complex by an amount corresponding to the additional components, and the cost of manufacturing it becomes expensive.